<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <button>按钮1</button>
  <button>按钮2</button>
  <button>按钮3</button>
  <script>
    var aButtons = document.querySelectorAll('button');
    console.log(aButtons);
    for (var i = 0; i < aButtons.length; i++) {
      // var j = i;
      aButtons[i].prop = i;
      aButtons[i].onclick = function() {
        console.log('点击按钮',this.prop);
      }
    }
  </script>
</body>
</html>
